How to Read a Milk Test Report — Fat, SNF, Acidity & More Explained
Learn to interpret a milk test report step by step. Understand what fat%, SNF%, CLR, acidity, and MBRT results mean and what action to take.
Every dairy plant receives hundreds of milk test reports every day — from incoming tankers, village collection points, and lab analyses. But for many new dairy technologists and plant managers, reading and interpreting these reports correctly isn’t always straightforward.
This guide breaks down each parameter on a standard milk test report, explains what it means, and tells you exactly what to do with the result.
The Standard Milk Test Parameters
A typical milk procurement test report from a dairy receiving dock in India contains:
- Fat % (by Gerber method)
- SNF % (calculated or by Lactometer)
- CLR (Corrected Lactometer Reading)
- Titratable Acidity %
- Temperature at receiving
- MBRT (on some reports)
- Organoleptic assessment (smell, appearance)
Let’s go through each one.
1. Fat % (Gerber Method)
What it means: The percentage of fat by weight in the milk. Higher fat = more value.
How it’s measured: Butyrometer (Gerber test) using concentrated sulphuric acid and amyl alcohol.
Normal ranges:
| Milk Type | Expected Fat % |
|---|---|
| Indian cow milk | 3.5 – 5.0% |
| Indian buffalo milk | 6.0 – 8.0% |
| Mixed milk | 4.5 – 6.5% |
What to do:
- ✅ Within range → Accept, record for payment calculation
- ⚠️ Lower than expected → Check CLR and SNF — possible water addition
- ❌ Below FSSAI minimum → Reject or divert to non-standard use
Pricing tip: Most cooperative dairies in India price milk on a fat + SNF matrix — each 0.1% fat typically varies the price by ₹0.20–0.50/litre.
2. SNF % (Solids Not Fat)
What it means: All milk solids except fat — primarily protein, lactose, and minerals.
How it’s calculated:
SNF (%) = (CLR / 4) + 0.25 × Fat% + 0.44 (Cow milk formula)
OR directly measured by Lactoscan / ultrasonic analyser.
Normal ranges:
| Milk Type | Expected SNF % |
|---|---|
| Cow milk | 8.0 – 9.0% |
| Buffalo milk | 8.5 – 9.5% |
| FSSAI minimum (toned) | 8.5% |
What to do:
- ✅ Within range → Accept
- ⚠️ SNF low but CLR normal → Possible seasonal variation or late lactation; monitor
- ❌ SNF and CLR both low → Water adulteration suspected — escalate to supervisory test
3. CLR (Corrected Lactometer Reading)
What it means: A measure of milk density. Pure milk is denser than water; water addition reduces density.
How it’s measured: Lactometer at standardised temperature (27°C). “Corrected” means adjusted for temperature.
CLR = LR + 0.2 × (T − 27) where T is the actual temperature
Normal ranges:
| Milk Type | Expected CLR |
|---|---|
| Cow milk | 26 – 32° |
| Buffalo milk | 28 – 34° |
| FSSAI minimum | 26° |
What to do:
- CLR 28–32° → Normal cow milk → Accept
- CLR 25–27° → Borderline → Run MBRT, check fat+SNF, escalate if multiple tests fail
- CLR < 25° → Water adulteration highly likely → Reject
4. Titratable Acidity (TA) %
What it means: The percentage of lactic acid in milk. Fresh milk has natural acidity; bacterial fermentation develops additional acidity.
How it’s measured: Titration with 0.1N NaOH using phenolphthalein indicator (IS 1479 method).
Normal ranges:
| Reading | Interpretation |
|---|---|
| ≤ 0.13% | Very fresh |
| 0.13 – 0.14% | Fresh — accept |
| 0.14 – 0.16% | Borderline — test MBRT |
| > 0.16% | Sour — Reject for fluid milk |
What to do:
- TA 0.13–0.14% → Accept for all products
- TA 0.14–0.16% → Accept only for heat-treated products (ghee, SMP); monitor trend
- TA > 0.16% → Reject — sour milk cannot be pasteurised for fluid milk
5. Temperature at Receiving
What it means: The temperature of the incoming milk. Cold milk = good cold chain = lower bacteria.
FSSAI guidelines: Received milk should be ≤ 7°C (or ≤ 10°C for short haul)
| Temperature | Action |
|---|---|
| ≤ 4°C | Excellent — cold chain maintained |
| 4–7°C | Acceptable |
| 7–10°C | Borderline — MBRT test mandatory |
| > 10°C | Reject or refer to quality manager |
6. MBRT (Methylene Blue Reduction Time)
What it means: An indirect measure of total bacterial load. Longer time = fewer bacteria = better quality.
| MBRT Result | Grade | Action |
|---|---|---|
| > 5 hours | Very Good | Accept for all products |
| 2–5 hours | Good | Accept; monitor |
| 30 min – 2 hours | Fair | Divert to heat-treated products only |
| < 30 minutes | Poor | Reject |
→ Use our MBRT Calculator to instantly determine the quality grade.
Making the Accept/Reject Decision
A simple decision matrix for receiving dock operators:
| All tests pass | → Accept | | One parameter borderline | → Conditional accept — supervisor approval required | | Any parameter fails hard limit | → Reject — issue rejection memo with test results | | Suspicion of adulteration | → Retain sample for confirmatory testing; escalate |
Always retain a 200 mL reference sample from every rejected consignment for 72 hours in case of supplier dispute.
Final Tips
- Calibrate instruments daily — lactometer, thermometer, and burette
- Composite samples correctly — agitate before sampling; avoid foam
- Record every result — FSSAI requires milk testing records for 2 years
- Never override rejections — one bad batch can contaminate an entire silo
Understanding your milk test report is the first line of defence for dairy quality. A well-trained receiving team catches problems before they enter the plant.